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authorHeiko Carstens <heiko.carstens@de.ibm.com>2017-03-27 09:48:04 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2017-03-30 08:18:59 +0200
commitd09c5373e8e4eaaa09233552cbf75dc4c4f21203 (patch)
tree6bb8d0f317d621a46e39ef5a9883a22559a5c7af /arch
parentca681ec860d6533b8debda4f6ab2e70e6d519d89 (diff)
downloadlinux-d09c5373e8e4eaaa09233552cbf75dc4c4f21203.tar.bz2
s390/uaccess: get_user() should zero on failure (again)
Commit fd2d2b191fe7 ("s390: get_user() should zero on failure") intended to fix s390's get_user() implementation which did not zero the target operand if the read from user space faulted. Unfortunately the patch has no effect: the corresponding inline assembly specifies that the operand is only written to ("=") and the previous value is discarded. Therefore the compiler is free to and actually does omit the zero initialization. To fix this simply change the contraint modifier to "+", so the compiler cannot omit the initialization anymore. Fixes: c9ca78415ac1 ("s390/uaccess: provide inline variants of get_user/put_user") Fixes: fd2d2b191fe7 ("s390: get_user() should zero on failure") Cc: stable@vger.kernel.org Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/s390/include/asm/uaccess.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index 136932ff4250..3ea1554d04b3 100644
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -147,7 +147,7 @@ unsigned long __must_check __copy_to_user(void __user *to, const void *from,
" jg 2b\n" \
".popsection\n" \
EX_TABLE(0b,3b) EX_TABLE(1b,3b) \
- : "=d" (__rc), "=Q" (*(to)) \
+ : "=d" (__rc), "+Q" (*(to)) \
: "d" (size), "Q" (*(from)), \
"d" (__reg0), "K" (-EFAULT) \
: "cc"); \